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Biomedical subjects

E Wisker

Publications and source records attributed to E Wisker.

16 recordsLinked to original sources
PubMed2003

[Probiotics].

The colonic flora is thought to play a key role in human health. Gut bacteria produce desirable as well as undesirable metabolites from fermentation and sometimes they may act as pathogens. Composition as well as activities of the gut bacteria can be influenced by nutrition. Prebiotics are food ingredients that selectively stimulate the growth of colonic bacteria regarded as beneficial, i. e. bifidobacteria and lactobacilli. Fructose polymers (fructo-oligosaccharides, inulin), galacto-oligosaccharides and soya oligosaccharides were shown to exert prebiotic activities. In adults, the growth of bifidobacteria was stimulated especially by inulin and fructo-oligosaccharides. Infant formulas containing galacto-oligosaccharides and inulin promoted the growth of bifidobacteria in faeces of bottle-fed infants and resulted in stool characteristics similar to those found in breast-fed infants. However, at present there is only limited knowledge on the long-term health consequences of increased counts of bifidobacteria. In adults, prebiotics can enhance the absorption of calcium from the colon. They can increase stool frequency and are mildly laxative. Prebiotic consumption is usually accompanied by mild flatulence and in sensitive persons by more severe gastrointestinal symptoms. In contrast to the results of animal experiments, a significant lipid-lowering action of fructo-oligosaccharides has not been found in humans. In animals, fructo-oligosaccharides have shown a favourable effect on experimental carcinogenesis. Whether or not these findings may apply to humans will be subject of future studies.

Anticarcinogenic Agents↗
PubMed2000

Short-chain fatty acids produced in vitro from fibre residues obtained from mixed diets containing different breads and in human faeces during the ingestion of the diets.

It was studied whether the type of bread (i.e. a low-fibre wheat-rye mixed bread and coarse or fine wholemeal rye bread) either as part of a diet or alone, had an influence on the short-chain fatty acids (SCFA) produced during in vitro fermentation. Fermentation substrates were dietary fibre residues obtained from diets and breads. In addition, it was investigated whether the faecal SCFA pattern in the inoculum donors, who ingested the experimental diets, could be predicted by in vitro fermentation. Yields of SCFA in vitro were 0.51-0.62 g/g fermented polysaccharide. In vitro, the molar ratios of butyrate were higher for the two high-fibre diets containing coarse or fine wholemeal bread than for the low fibre diet containing wheat-rye mixed bread; the difference was significant for the coarse (P < 0.01), but not for the fine bread diet (P = 0.0678). The coarse wholemeal bread alone produced a higher molar ratio of butyrate than the fine wholemeal bread (P < 0.05) and the wheat-rye mixed bread (P < 0.01). Ingestion by the inoculum donors of the diets containing wholemeal bread led to higher faecal butyrate ratios (molar ratios: coarse bread diet 19.6, fine bread diet 17.7) compared with the wheat-rye mixed bread-containing diet (14.9), but the differences between the diets were not significant. For the diets investigated, there were no significant differences between faecal and in vitro SCFA patterns.

Acetates↗
PubMed1998

Fermentation of non-starch polysaccharides in mixed diets and single fibre sources: comparative studies in human subjects and in vitro.

The present study investigated whether the extent of fermentation of NSP in human subjects could be predicted by an in vitro batch system. Fibre sources studied were five mixed diets containing different amounts and types of fibre and three single fibre sources (citrus fibre concentrate, coarse and fine wholemeal rye bread). Fermentation in human subjects was determined in balance experiments in women who were also donors of the faecal inocula. In vitro fermentations were performed with fibre residues prepared from duplicates of the fibre-containing foods consumed during the balance trials. Fermentation of total NSP in vivo was between 65.8 and 88.6% for the mixed diets and 54.4, 58.0 and 96.9% for the coarse and fine wholemeal rye breads and the citrus fibre concentrate respectively. For the mixed diets and the citrus fibre concentrate, mean differences between the extent of NSP degradation after 24 h in vitro incubation and that in vivo were between -0.7 and 5.0%. Differences were significant for one diet (P < 0.05). For the wholemeal rye breads, the fermentation in vitro exceeded that in vivo significantly, but the magnitude of the difference in each case was small and without physiological importance. Particle size of breads had no influence on the extent of NSP degradation. These results indicate that the in vitro batch system used could provide quantitative data on the fermentation in vivo of NSP in mixed diets and some single fibre sources. An in vitro incubation time of 24 h was sufficient to mimic the NSP degradation in vivo.

Adult↗
PubMed1997

Energy values of non-starch polysaccharides: comparative studies in humans and rats.

Energy values of non-starch polysaccharides (NSP) were estimated from NSP fermentability and from digestible energy balances in human subjects and in rats. During four studies, humans consumed four low fiber control diets and six high fiber diets. For the rat diets, duplicates of the foods consumed by humans were mixed together, freeze-dried and ground. Calculated from fermentability, partial digestible energy values of NSP in humans and rats, respectively, were 8.2 +/- 1.3 and 5.7 +/- 1.2 (P = 0.0013, fruits and vegetables), 11.4 +/- 0.7 and 5.7 +/- 3.2 (P = 0.0001, citrus fiber), 5.0 +/- 2.1 and 2.2 +/- 3.3 (P = 0.0429, barley fiber at high protein intake), 4.4 +/- 1.8 and 2.4 +/- 2.0 (P = 0.0561, barley fiber at low protein intake), 6.7 +/- 1.4 and 7.6 +/- 1.2 (P = 0.296, coarse whole meal rye bread), and 7.1 +/- 0.6 and 6.1 +/- 1.7 (P = 0.157, fine whole meal rye bread) kJ/g NSP. Calculated from energy balances, partial digestible energy values of NSP in humans and rats, respectively, were 2.1 +/- 3.5 and -5.0 +/- 4.0 (P = 0.026, fruits and vegetables), 10.7 +/- 5.1 and 1.4 +/- 5.6 (P = 0.003, citrus fiber), 1.6 +/- 5.1 and -17.8 +/- 8.6 (P = 0.0001, barley fiber at high protein intake), -2.6 +/- 4.9 and -9.3 +/- 8.2 (P = 0.044, barley fiber at low protein intake), -3.0 +/- 7.0 and 0.9 +/- 2.5 (P = 0.27, coarse whole meal rye bread), and 0.9 +/- 5.1 and 0.6 +/- 3.7 (P = 0.89, fine whole meal rye bread) kJ/g NSP. Net energy values were 70% of digestible energy values. Differences between species were significant for NSP in fruits and vegetables, citrus fiber, and barley fiber at high protein intake. Most energy values calculated from energy balances were significantly lower than values calculated from NSP fermentation, with differences being greater in rats than in humans. Thus, the energy values of some types of NSP contained in mixed diets could not be estimated accurately from NSP fermentability either in humans or rats. In addition, our results suggest that the rat is not always a suitable model of humans for predicting energy values of NSP in mixed diets.

Adult↗
PubMed1997

Fermentation in human subjects of nonstarch polysaccharides in mixed diets, but not in a barley fiber concentrate, could be predicted by in vitro fermentation using human fecal inocula.

The fermentation of nonstarch polysaccharides (NSP) contained in a low fiber diet, two high fiber diets high or low in protein, and a barley fiber concentrate was determined in balance experiments in six women and in an in vitro batch system using fecal inocula obtained from these same women. In vitro fermentations were performed with fiber residues prepared from duplicates of the fiber-containing foods consumed during the balance trials. Fermentation of total NSP in humans was 83.8 +/- 0.9% (low fiber diet), 61.8 +/- 3.6% (high fiber diet high in protein), 59.2 +/- 3. 9% (high fiber diet low in protein) and 31.2 +/- 7.4% (barley fiber concentrate). Fermentation in vitro differed from fermentation in humans by -4.0 +/- 1.6% (low fiber diet, P < 0.05,), 4.9 +/- 3.7% (high fiber diet high in protein), 8.8 +/- 3.0% (high fiber diet low in protein, P < 0.01) and 19.7 +/- 8.0% (barley fiber concentrate, P < 0.05). Differences between in vivo and in vitro fermentation were most pronounced for NSP-glucose, i.e., cellulose. Production of short-chain fatty acids in vitro corresponded to the fermentability of NSP. The yield of short-chain fatty acids per gram of fermented NSP was similar for the diets (8.8-9.4 mmol) but lower for the barley fiber concentrate (7.4 mmol, P < 0.05). Although differences between the fermentation measured in humans and in vitro were significant for two diets, the magnitude of the differences was such that fermentation of NSP in mixed diets could be predicted with sufficient accuracy in vitro, whereas agreement between the fermentation in vivo and in vitro of NSP in the barley fiber concentrate was not satisfactory.

Adult↗
PubMed1996

Digestibilities of energy, protein, fat and nonstarch polysaccharides in a low fiber diet and diets containing coarse or fine whole meal rye are comparable in rats and humans.

The apparent digestibility of energy, protein, fat and nonstarch polysaccharides (NSP) of a low fiber diet and two high fiber diets containing coarse or fine whole meal rye bread was studied in experiments with humans and rats. Human subjects consumed the experimental diets for 3 wk each in a 3 x 3 cross over design. For the rat diets, duplicate portions of the foods consumed by the human subjects were mixed together, freeze dried and ground. There was a good agreement in the digestibility of energy (humans: 94.7 +/- 0.9, 91.2 +/- 1.2 and 91.6 +/- 1.4%; rats: 95.0 +/- 0.8, 92.5 +/- 1.4 and 91.7 +/- 1.8%) and fat (humans: 95.2 +/- 1.5, 94.4 +/- 1.0 and 94.8 +/- 2.5%, rats: 95.4 +/- 0.9, 94.0 +/- 0.4 and 94.0 +/- 0.4%) for the low fiber diet and the diets containing coarse or fine whole meal bread, respectively. Apparent and true digestibility of protein was consistently lower (P < 0.0001) in humans (apparent digestibility: 90.6 +/- 1.5, 86.2 +/- 1.4 and 86.3 +/- 2.3%; true digestibility: 95.1 +/- 1.5, 90.7 +/- 1.4 and 90.8 +/- 2.2%) than in rats (apparent digestibility: 92.3 +/- 1.1, 89.4 +/- 0.9 and 88.9 +/- 1.0%; true digestibility: 98.3 +/- 1.1, 94.9 +/- 0.9 and 94.2 +/- 1.0%) for all three diets. The digestibility of NSP tended to be lower (P < 0.066) in rats than in humans for the diet containing fine whole meal bread (rats: 59.6 +/- 8.0%, humans: 68.0 +/- 5.2%) and the low fiber diet (rats: 72.1 +/- 10.8%; humans: 80.5 +/- 7.1%), whereas it was similar in both species for the diet containing the coarse whole meal bread (rats: 66.1 +/- 6.0%; humans: 65.8 +/- 9.3%). In spite of some differences in digestibility values, our results suggest that the rat is a suitable model for humans to predict digestibility of nutrients in mixed diets containing cereal fiber sources.

Adult↗
PubMed1994

Fibre-mediated physiological effects of raw and processed carrots in humans.

Fibre-mediated physiological effects of raw and processed carrots were investigated in twenty-four young women under strict dietary control in two randomized crossover studies. For 3 weeks between 405 and 688 g of either raw frozen, blanched or canned carrots (first study), or raw or raw frozen carrots (second study) were consumed in addition to a low-fibre basal diet. Carrots provided 15 g dietary fibre (DF)/d. Total DF intake was 16.0 to 19.0 g (control periods) and 31 to 34 g (experimental periods). Faecal bulking effects of raw and processed carrots were similar (between 2.4 and 3.7 g additional stool/g carrot fibre in the diet). Faecal excretion of dry matter, fibre, and protein also increased significantly during carrot consumption. Fermentability of carrot fibre constituents was high (91-94%) and independent of processing, in spite of differences in the distribution of soluble and insoluble fibre and in the texture of raw and processed carrots. There was no effect of either type of carrot on serum total and high-density-lipoprotein-cholesterol or on faecal bile acid excretion.

Adult↗
PubMed1994

Digestibility of energy, protein, fat and non-starch polysaccharides in mixed diets: comparative studies between man and the rat.

The apparent digestibility of energy, protein, fat and non-starch polysaccharides (NSP) of low and high dietary fibre (DF) mixed diets were studied in three series of experiments with man and the rat. Low DF diets were used as control diets in each experimental series and the DF level was increased by adding fruits and vegetables (Study 1), citrus fibre concentrate (Study 2) and insoluble barley fibre (Study 3). In Study 3 the high DF diet was fed at two protein levels. There was in most cases good agreement between the digestibility of energy between man and the rat, with the digestibility of energy of the low DF control diets of 0.941-0.950 in man compared with 0.933-0.952 in the rat and of the high DF diets of 0.897-0.931 in man and 0.865-0.920 in the rat. The biggest difference in digestible energy between the two species was found for the diet enriched with fruits and vegetables (0.032 absolute units) and citrus fibre concentrate (0.025 absolute units). Apparent digestibility of protein was slightly lower in man than in the rat for all diets in Studies 1 and 2. In Study 3, however, apparent digestibility of protein was consistently lower in man than in the rat with differences in absolute digestibilities between the two species varying from 0.023 (high DF/high protein) to 0.071 (high DF/low protein). The digestibility of fat was the same in man and in the rat in all but the high DF diet of Study 2. The rat appears to have a lower capacity to digest fibre polysaccharides than man and the digestibility of NSP was consistently lower in the rat than in man. The biggest difference between the two species was found for the diets in Study 2 where the digestibility of NSP in man was measured to be 0.774-0.885 compared with only 0.501-0.517 in the rat. For the other diets the differences in NSP digestibility were 0.077-0.137 absolute units. In spite of some differences between man and the rat in their ability to digest nutrients the various diets are ranked in the same order by the two species.

Adult↗
PubMed1993

[Is there a correlation of dietary fiber to the calculation of calorific value of food? Comparison of the experimental determination and the calculated metabolizable energy of 16 diets with different fiber content].

The metabolizable energy (ME) of 16 diets containing various amounts and sources of dietary fibre was calculated by different energy assessment procedures and determined experimentally in balance studies in humans. ME was calculated by the German procedure (section 35 LMBG; 4/9/4) and by the British procedure (4/9/3.75). In addition, both calculation procedures were modified to take into account the energy value of dietary fibre. Dietary fibre was multiplied by an energy conversion factor of 1 or 2 kcal/g, respectively. The best agreement between measured and calculated ME was obtained when a conversion factor of 1 kcal/g fibre (German procedure) or of 2 kcal/g (British procedure) was used.

Adult↗
PubMed1991

Calcium, magnesium, zinc, and iron balances in young women: effects of a low-phytate barley-fiber concentrate.

The effects of a low-phytate barley-fiber concentrate on calcium, magnesium, and zinc balances and on apparent iron absorption were measured by balance experiments. During the three experimental periods of 22 d each, all subjects consumed the basal diet alone, the basal diet with 15 g barley fiber (high-fiber, high-protein diet), and a modified basal diet containing less protein with 15 g barley fiber (high-fiber, low-protein diet), respectively. The mean daily intake of the cations was 24.4, 25.4, and 22.9 mmol Ca; 10.4, 10.1, and 10.0 mmol Mg; 165.2, 166.8, and 119.3 mumol Zn; and 154.0, 186.2, and 154.0 mumol Fe, respectively. Mean balances were 0.2, 1.9, and -0.8 mmol Ca; 0.3, -0.2; and -0.5 mmol Mg; 3.0, -4.6, and -18.4 mumol Zn. The mean apparent iron absorption was 16.1, 5.4, and -23.2 mumol when these three diets, respectively, were consumed.

Adult↗
PubMed1990

Metabolizable energy of diets low or high in dietary fiber from fruits and vegetables when consumed by humans.

The metabolizable energy (ME) of two diets, which differed in their content of dietary fiber mainly from fruits and vegetables, was determined in balance experiments in eight young women. The ME of the diets was also calculated by the specific factors of Merrill and Watt, by the general factors of Atwater, by the modification of Atwater's procedure used in the Federal Republic of Germany, and also by the equations of Southgate, of Miller and Payne, and of Miller and Judd. The daily intake of fruits, vegetables and potatoes was 505 and 1235 g with the low and the high fiber diets, respectively. Normally, young German women consume only 350 g of these foods each day. Dietary fiber intake was 18.8 g/d with the low fiber diet and 52.0 g/d with the high fiber diet. Daily gross energy intakes were 8540 and 8916 kJ (2041 and 2131 kcal) with the low and the high fiber diets, respectively. The apparent digestibility of energy was lower when the high fiber diet was consumed. Measured ME was 7665 and 7544 kJ/d (1831 and 1802 kcal/d) with the low and high fiber diets, respectively. It was calculated that fiber from fruits and vegetables contributed to ME about 3 kJ (0.7 kcal) per gram of fiber. On the average, the ME of the low fiber diet could be predicted by all calculation procedures except the formula of Miller and Judd. The ME of the high fiber diet could best be predicted by the specific factors of Merrill and Watt and by the Southgate formula.

Adult↗
PubMed1988

Metabolizable energy of diets low or high in dietary fiber from cereals when eaten by humans.

The metabolizable energy (ME) of two diets that differed in their content of dietary fiber (DF) from cereal products was measured in balance experiments in six human subjects. DF intake was 19.7 g/d with the low fiber diet and 48.3 g/d with the high fiber diet. Daily gross energy intakes were 2114 kcal (8845 kJ) and 2341 kcal (9795 kJ)/d with the low and the high fiber diets, respectively. DF contributed 83 kcal (347 kJ) and 203 kcal (849 kJ) to daily gross energy intake with the low and the high fiber diets, respectively, when heat of combustion of DF of 4.2 kcal (17.6 kJ)/g was assumed. Increasing the intake of DF resulted in an increase in stool weight and a greater fecal energy loss. Total energy losses were 253 kcal (1056 kJ) and 409 kcal (1711 kJ)/d with the low and the high fiber diets, respectively. ME provided by the low and the high fiber diet were 1861 kcal (7786 kJ) and 1932 kcal (8083 kJ)/d. The total increase in energy losses due to the increase in DF consumption exceeded the gross energy provided by additional DF. Compared with the low fiber diet, ME provided by protein and fat was decreased during the high fiber diet. Calculation of the apparent digestibility of DF indicated that fiber may have provided ME in the form of short-chain fatty acids during the low as well as during the high fiber intake. However, estimation of the amount of fecal gross energy indicated that available components of the diet, such as starch, must have been utilized incompletely during both experimental periods.

Adult↗
PubMed1984

[Effects of various methods on the determination of dietary fiber and available carbohydrates on the calculation of the energy content of bread].

The dietary fiber content of German breads was determined by two different methods. With a modified NDF-method 60% of total dietary fiber (determined by an enzymatic-chemical procedure) are detected. For estimation of the physiological fuel value the main components of breads were determined by analysis. In addition, the carbohydrates were determined by difference, using various methods of calculation. For the estimation of the caloric value, different calorie conversion factors are used.

Amylases↗
PubMed1983

[Caloric value and dietary fiber content of cereals, flours and breads].

A new method for the determination of the caloric values of foods is proposed. To date it had been suggested that with an increase in the dietary fiber content of foods the intestinal absorption of proteins and fats is reduced. This has to be revised in the light of recent experimental results. The new method leads to higher energy values for fats and proteins whereas for carbohydrates lower figures are obtained. This leads to considerable deviation in the energy content of foods from the values in present tables, especially for foods rich in dietary fiber.

Bread↗
PubMed1980

[A method for the determination of tartrazine in candies and pudding mixes (author's transl)].

The use of food additives is viewed increasingly from a critical point of view. In some countries, stronger regulations with limitations for the use of synthetic coal-tar dyes are planned or exist already. For that reason, a quantitative method for the determination of tartrazine (E 102) is needed for supervision of food quality. A method is described using as its steps extraction of the dyestuffs from the samples, chromatography on silicagel plates and automatically recorded densitometry. In candies amounts of up to 285 mg tartrazine/kg and in pudding mixes up to 1223 mg tartrazine/kg were found.

Azo Compounds↗